Very large value for xs:Integer are wrongly considered as invalid

When trying to validate a XML with a very large value for xs:Integer (e.g. 17041253445193374908) validation will fail with the following message:

"Content of element {http://www.w3.org/2000/09/xmldsig#}X509SerialNumber does not match its type definition: 17041253445193374908 is not valid according to xs:integer"

The problem comes from the fact xs:Integer is internally stored as qint64, which cannot hold such values.
But from my understanding, xs:integer isn't bounded (only xs:int is).

Then Qt fails to convert the value to a xsInteger internally (in qinteger.cpp Integer::fromLexical)